1. Technical Field
The present invention relates to a magnetism measuring device, a manufacturing method of a magnetism measuring device, a gas cell, and a manufacturing method of a gas cell.
2. Related Art
An optical pumping type magnetism measuring device which irradiates a gas cell, in which an alkali metal gas is sealed, with linearly polarized light and measures a magnetic field according to a rotation angle of a polarization plane is known (for example, refer to JP-A-2012-183290). JP-A-2012-183290 discloses the configuration of a gas cell, in which an ampoule containing an alkali metal sealed therein is accommodated in a cell, the cell is sealed, the ampoule is irradiated with laser light so as to form a through-hole in a glass tube of the ampoule, and the alkali metal in the ampoule is vaporized to fill the inside of the cell with the vapor (gas) thereof.
According to the description of JP-A-2012-183290, the cell is formed by joining a package (container) and a lid (lid portion), which are made of glass, to each other using a sealing material such as low-melting-point glass. In order to enhance non-relaxation characteristics, a coating layer is formed on the inner wall of the cell by allowing a coating material made of a chain saturated hydrocarbon (paraffin or the like) to flow into the cell from a flow passage. In addition, the vapor (gas) of the alkali metal is allowed to diffuse in the cell, and thereafter the flow passage of the coating material is sealed by the sealing material such as low-melting-point glass.
However, the alkali metal has high reactivity, and the low-melting-point glass generally has low chemical resistance. Therefore, when the inside of the gas cell is filled with the gas of the alkali metal, there may be a case where a chemical reaction between the alkali metal and the low-melting-point glass occurs. When the chemical reaction between the alkali metal and the low-melting-point glass occurs, the amount of the gas of the alkali metal in the gas cell is reduced due to a chemical change in the alkali metal, and the gas of the alkali metal leaks to the outside of the gas cell due to the deterioration in the seal caused by a chemical change in the sealing material (the low-melting-point glass). As a result, there are problems in that there is concern that the manufacturing yield of the gas cell and the magnetism measuring device may be reduced or there is concern that the sensitivity of the magnetism measuring device may not be maintained for a long period of time due to a reduction in the service life of the gas cell.